Edge bitted key blanks are normally cut by cutting machines which preposition the key blank in a jawed clamp or vise. The positioning holds the edge of the key blade which is to be cut for bitting a fixed position relative to a clamped original key.
Most often the keys are positioned with respect to either the tip end of the blade or to a shoulder at the head end of the blade since bitting measurements along the length of the blade are normally specified as having their positions at specified distances from one of those two base points, i.e. either the blade tip or the blade shoulder. Precise positioning of the key edge is critical to the proper cutting of the bitting. In the most commonly used standard key cutting machines, a moveable vise supporting carnage is provided having spaced apart vise jaws, one for the original key and one for the uncut key blank. With the two keys properly positioned between the jaws of each vise, the two jaws are moved in unison with the cut key being moved both inwardly against a fixed follower and axially along the length of the blade so that the vises move with respect to the follower both inwardly and outwardly as the carriage is moved axially to move the original key along its length against the follower.
A cutting wheel is spaced from the follower a distance equal to the spacing between the original key vise and key blank vise. Since the original key clamp vise and the key blank clamp vise are fixed for movement together, the key blank edge will be urged against the rotating cutter both inwardly and outwardly and in direct proportion to the movement of the cut original key against the follower. In such standard cutting machines the keys normally lie in the same plane and are axially aligned their longitudinal axis from head to tip with the follower spaced to one side of the machine and the cutting blade spaced to the other side of the machine, both open to a front. The clamping vises are received at the top of a yolk-shaped carriage, which is pivotally attached towards a base of the machine and may be moved manually or automatically.
In other key cutting machines, the key to be cut may be clamped between clamping jaws that engage the head end of the key with the blade of the key projecting outwardly from the clamping jaws. Again, the positioning of the key head is generally either based upon an abutment of the key tip with a fixed abutment spaced from the head clamp or by an abutment of the key shoulder against a fixed point. In some such machines the cutter blade may move along the length of the key blade and may move inwardly and outwardly with respect to the center line of the key blade, normally following a profile determined from a corresponding bitted edge of the original key while in other machines the key moves with respect to the cutter. While various proposals have been made for determining the profile of the bitted edge of the original key, the most common solution is the use of an edge follower which is positionally fixed either mechanically or electronically to the cutting device, usually a wheel. While various other suggestions, including laser cutting and the like have been made, it is common to key cutting machines to fixedly position the key to be cut in a clamped position where its blade's position with respect to the cutting modality is determined, at least in part, with reference to either the tip of the key or a shoulder of the key or both. It is also known to cut both sides of a key blade at the same time for keys having identical bitting on each edge. For example, as shown in U.S. Pat. No. 5,443,339, which also teaches that the shoulder may be cut at the same time on an unshouldered key blank.
Unfortunately experience has shown that these prior systems often result in miscut keys. This is almost always due to a mispositioning of either the original key or of the key blank in its clamp vise. Since both the original key vise and the key blank vise are in fixed relationship to one another on the carriage, any misalignment between either key and its properly seated position in its vise will cause the resultant key cut from the key blank to have a different bit profile than the original since as the carriage is moved inwardly and outwardly and laterally of the follower, with the follower always in contact with the bitted edge of the original key, the movement of the key carried in the key blank jaws will be identical to the movement of the original key, and since the cutter wheel cutting edge is aligned with the key engaging point of the follower, the inevitable result of any mispositioning of either one or both of the keys in its associated vise clamp is that the bitted edge profiles will not match after cutting, with the likely result that the newly cut key will not operate in the lock and will need to be discarded.
While it is known to use key cutting machines in which the keys are held in vises connected to a pivotal and laterally moveable carriage, with the key blade or blade and head received between the jaws of the clamp such that a single working edge of the key extends from the clamp, other clamping methods are also known where the key instead of being moved laterally across the front of the key cutting machine would be moved longitudinally with the key blade projecting into the cutting machine. In such machines the key blade may be simultaneously or sequentially cut on both sides as the clamping mechanism is applied to areas of the key, generally the head, other than the bitted or working edges. Oftentimes keys are provided with a shank extending between the head and the bitted edge, which begins at or includes a shoulder, and clamping can be made at the head, the shank, the tip or centrally of the blade along its length since bit cutting normally does not reach to the center line of the blade. It is, however, common in known clamping systems, whether they clamp at the blade, head, shank, or combinations thereof, that mispositioning between the clamped position of the original key and the clamped position of the key blank to be cut is a common problem.
It would therefore be an advance in the art to provide a locating system for positioning the keys, both the original bitted key and the key blank, in the clamp vises that minimizes the possibility of misalignment or mispositioning of the keys with respect to the vises.